Agriculture Reference
In-Depth Information
Table 12.2 Swine wastewater and effluent characteristics in various processing stages (Zhang
et al.
2011
)
NH
4
+
-
N
pH
SS
COD
K
Na
Ca
Mg
Raw water
7.25-
8.9
386-
3,306
60-
7,722
823-
900
572.93-
674.9
364-
470
177.3-
260.2
97-105
Anaerobic
effluent
6.82-
8.5
154-
75
305-
2,266
740-
810
300.8-
462.8
338-
402.2
87.8-
116.4
63.12-
100
Effluent of eco-
logical pond
6.68-
9.3
28-
624
164-
1,960
62-
685
227.93-
398.3
394-
540
119.6
84.86-
109.84
In our experiment, we applied the methods presented in existing works for the
treatment of wastewater from a piggery in Tianjin. The characteristics of the swine
wastewater and effluent are shown in Table
12.2
. The NF membrane model used
was ESNA1-4040 (Nitto Denko) aromatic polyamide, the water production was
7.4 m
3
/day, the desalination rate was 85-95 %, and the effective membrane area
was 7.9 m
2
.
We employed nano-MgO-activated carbon NF membrane to remove various
pollutants from swine wastewater (Zhang et al.
2011
). The farm ecological pond
water was diluted 30-fold and poured into the raw water tank. The vacuum pump
was mounted onto the mixing tank. The water was only initially added to the nano-
MgO, and subsequent addition of water was not required. The mixer was operated
to stir the water at 80 rpm for 5 min, and then, the water was allowed to stand for
20 min. Then, by using the vacuum pump, the water was continuously mixed and
passed through the sand filtration column, activated carbon filtration column, and
NF membrane component (Fig.
12.7
). Simultaneously, the metering pump was
operated to pump KH
2
PO
4
into the NF membrane pipe at a flow rate of 2 L/h.
The dosages of nano-MgO and KH
2
PO
4
were 0.1 kg and 0.05 mol/L, respectively.
The removal of NH
3
-N by the combination process (Fig.
12.8
) and the KH
2
PO
4
index showed a similar trend, and the concentration of organic matter and NH
3
-N in
water gradually decreased after subjecting to nano-MgO, filtration, and NF. In
particular, after filtration through the NF membrane, the concentration of organic
matter and NH
3
-N decreased by 85-90 and 70-85 %, respectively, and remained in
a stable concentration range, and the water reached the quality of irrigation water.
However, with respect to water treated by nano-MgO and filtration, the concentra-
tion of NH
3
-N and KH
2
PO
4
index showed a gradual increasing trend. This finding
suggested that with the decrease in nano-MgO consumption and medium adsorp-
tion, the pollutants removal efficiency of the NF membrane pretreatment process
decreased. It should be noted that after the quantity of the processed water reached
1m
3
, the organics removal capacity of nano-MgO was stable at about 40 %. These
findings (An et al.
2011
), along with prior screening test results, indicate that nano-
MgO removes organic matter by adsorption and oxidation.
As mentioned earlier, the use of nano-MgO increased water turbidity; however,
after the two-stage filtration, the turbidity of water decreased to about 1 NTU, and
after filtration using NF membrane, no turbidity could be detected in the effluent.
